Scientists in
Australia have found that some babies at risk of sudden infant
death syndrome, or SIDS, have low levels of an enzyme called
butyrylcholinesterase (BChE) in their blood. Their study, published May 6 in
the journal eBioMedicine, could pave the way for newborn screening and
interventions if the results are corroborated by further research.
اضافة اعلان
“It’s the first
time we’ve ever had a potential biomarker for SIDS,” said Dr. Carmel
Harrington, who led the research at the Children’s Hospital at Westmead in
Sydney.
Researchers have
been trying to chip away at the biological underpinnings of the puzzling
syndrome for decades. And while
public health campaigns have drastically
reduced the incidence of SIDS, it remains a leading cause of sudden and
unexpected death in infants under the age of 1 in Western countries.
One of the reasons
that
SIDS remains so tragic and mysterious is because it is probably not caused
by a single biological mechanism but by a combination of factors that come
together in a perfect storm, said Dr Thomas Keens, a pediatric pulmonologist at
Children’s Hospital Los Angeles. Previous studies have pointed to low activity or
damage in parts of infants’ brains that control heart rate, breathing and
arousal from sleep, for instance, as well as to environmental stressors such as
soft bedding or secondhand smoke.
“The thinking
among researchers is that some babies die from SIDS because they don’t wake up
in response to a dangerous situation when they’re asleep,” Keens said.
To test if there
was something inherently different in SIDS babies, Harrington and her
colleagues compared dried blood samples from the newborn heel prick test of 655
healthy babies, 26 babies who died from SIDS and 41 babies who died from
another cause. They found that about nine out of 10 babies who died of SIDS had
significantly lower BChE levels than did the babies in the other two groups.
“I was just stunned,”
said Harrington, who has been searching for clues and crowdfunding for her
research for nearly 30 years, since she lost one of her own children to SIDS.
“Parents of SIDS babies carry a huge amount of guilt because essentially their
child died on their watch. But what we’ve found with this study is that these
infants are different from birth, the difference is hidden, and nobody knew
about it before now. So it’s not parents’ fault.”
The new findings
add support to researchers’ hypothesis that babies who die from SIDS have
problems with arousal, said Dr Richard Goldstein, a pediatric palliative care
specialist at Boston Children’s Hospital. BChE plays a role in the availability
of important neurotransmitters in the brain’s arousal pathway. Low levels of the
enzyme could indicate that the
brain is not able to send out signals telling a
baby to wake up and turn her head or gasp for breath. “But we need a lot more
research before we can understand its actual significance,” Goldstein said.
While the study
identifies an important chemical marker in a small group of infants, it is too
soon to say if widespread testing for BChE will be helpful.
For one,
scientists and doctors do not know what a “normal” level of the enzyme looks
like. And because the Australian researchers did not have access to fresh blood
samples for BChE, they did not measure absolute levels of the enzyme. There was
also overlap between the infants. Some of the babies who died from SIDS had
BChE levels within the same range as the babies who did not die.
“If you’re going
to test every baby who’s born, you want the results to stand out as abnormal
only for babies who are at very high risk,” Keens said. Even if further studies
helped fine-tune the test for BChE to accurately distinguish between babies who
might die from SIDS and those who might go on to live
healthy lives, doctors
and parents would still be faced with the issue of what to do next. There is no
intervention or treatment for low BChE levels.
Much of the advice
for preventing SIDS remains the same, Keens said. Follow safe sleep
recommendations like laying your baby down on their back — both at nap time and
at night. Remove loose sheets, blankets, pillows, bumper pads, and soft toys
from your baby’s sleep area. And consider keeping your baby in the same room as
you at night for at least six months or, ideally, until your baby turns 1 years
old.
The
American Academy of Pediatrics also recommends avoiding exposure to smoke, alcohol, and illicit
drugs during pregnancy; breastfeeding; immunizing routinely; and using a
pacifier to reduce the risk of SIDS.
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